<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .parents {
        height: 340px;
        width: 570px;
        background-color: palevioletred;
        display: flex;
        box-sizing: border-box;
        flex-direction: column;
        flex-wrap: wrap;
        /* 在 flex-wrap: wrap;情况下不生效 */
        /* align-items: center; */
        justify-content: center;
        align-content: center;
    }

    .child {
        height: 100px;
        width: 200px;
        background-color: pink;

    }
</style>

<body>
    <div class="parents">
        <div class="child"></div>
        <div class="child"></div>
        <div class="child"></div>
        <div class="child"></div>
        <div class="child"></div>
    </div>
</body>

</html>